PTC heaters of varied constructions have been known for some time and they have generally been complex in construction involving various combinations of materials such as vitreous or ceramic potting compounds and spring-like elements for urging metallic terminals into contact with the PTC heating element. The following are typical of such patents: U.S. Pat. Nos. 3,214,719; 3,442,014; 3,564,199; 3,824,328; 3,835,434; 3,940,591; 3,996,447; 4,086,467; 4,104,509; 4,147,927.
It has been the usual practice in crankcase heaters, such as used in air conditioners, refrigerators and heat pumps to encapsulate the heaters in a rigid ceramic insulating body. To fit such rigid ceramic heaters into the rigid metallic wells of crankcases, it has been the practice to coat the ceramic with a thermally-conductive grease. The conductive grease is used to minimize the air space or clearance between the rigid outer heater surface and the wall of the crankcase well which, if not eliminated, would act as a thermal-insulating barrier to heat transfer.
The principal object of this invention is to provide a PTC-type crankcase heater of improved and simplified construction.
Another object of this invention is to provide a PTC type crankcase heater of the above type which lends itself to a simple and economical manufacturing process.
A further object of this invention is to provide an improved process for fabricating PTC-type crankcase heaters.